Apparatus for grinding and polishing glass



' APPARATUS FOR GRINDING AND POLISHING GLASS Louis Thehault, Sucy-en-Brie, France, assignor to Compagnie de Saint-Gobain, Paris, France Filed Sept. 15, 1958,:Ser.:No. 761,121

9 Claims. (Cl. 51-119) :a circular.:translatorymovement which, in preferred practice, engages the surface of glass sheets or platesxas they travel with a rectilinear movement. In certain known embodiments of such apparatus two points of the tool are connected tozdriving means which are compelled to travel with a translatory motion along closed directing .curves such as circular paths "having radii of the same length,in phase, and at the same speed.

The realization of such identical, synchronized motions of the two driving means, when driven by the same motor has proved to be difficult, since the relations between the two driving means must be maintained with great accuracy if the apparatus is to be successfully operated. The use of two synchronous motors, each of which is drivingly connected to its respective driving means, which is simpler from a mechanical point of view, does" not appear to have given satisfactory results.

The present invention has for an object the provision of an improved combination of a grinding and/ or polishing tool and a novel driving mechanism therefor which drives it along closed directing curves, as with a circular t-ranslatory motion, the apparatus eliminating the abovedescribed ditficulties in the driving mechanism for the tool.

The above and further objects of the invention will be understood upon consideration of the drawings, which show one, non-limiting, illustrativeform of the apparatus of the invention.

In the drawings:

Fig. l is asomewhat schematic view in plan of the main portion of the apparatus, the main driving shaft for the tool being shown in horizontal section, and the driving motor for the shaft being omitted in such figure;

Fig. 2 is a view in vertical section through a portion of the apparatus of Fig. 1, the section being taken along line 2-2 of Fig. l; and

Fig. 3 is a fragmentary view in side elevation of the apparatus of Fig. 1.

In accordance with the invention, the tool is driven by a single driving means such as a crank, cam, or the like, which compels one of the points of the tool to describe a circle. Means are provided to prevent all rotation of the tool around such point as a center, that is, to require the tool always to move parallel to itself.

One embodiment of the apparatus of the invention has the tool-driving and tool-guiding means so constructed and arranged that a straight line along the tool, preferably a straight line parallel to the major axis of the tool when the tool is rectangular, remains constantly parallel to itself during the described circular translatory movement of the tool.

In one embodiment of the invention, the tool-guiding means is provided by an articulated parallelogram. Two of the adjacent corners of the parallelogram are mounted on fixed axes, and the two other corners of the parallelogram are pivotally connected to slides reciprocably atentf Patented-Oct. 11, .1960

ice

.2 m ounted 'on-guides fixed on the tool, such guides lying alongan axis :parallel to the major axisof the tool.

Turning now to the drawings, there is there showman illustrative embodiment jof;apparatus in accordance with the invention. A glass grinding and/orxpolishing'tool 1 is driven, preferably at its longitudinal and lateral center, by a vertical shaft 4 having an eccentric, specifically a crank arm 3.thereon,1the crank pin 2 :of the crank being journalled on the central upper portion of the tool. .Al- .ternatively, ,thepinizrmay be1fixed to' tool :1,and'the upper end of'pin.2;may be 'journalledzin the outer. :end of crank 3. The shaft 4 :is journalled in afixed :support 14, as shown in Fig. 3, and is :driven, .for example, by anelectric motor :connected thereto. Upon rotation of shaft 4'by;mot0r 15, 'the center of crank pin Zdescribes a circle 5, andcompels the central zone of tool 1' to rotate in such circle. s

Mounted on the upper surface of tool 1 are longitudinally extending guides 6 the axes of the guides coinciding and lying along-the major axis x-x of the tool .1. A pair of guide-engaging slides .7, are mounted to reciprocate along the respective -guides.6. Each slide 7 carries a.cen tral, upwardly extending trunnion pin 8, on which are freely pivoted the ends of two parallel links or arms 9 which have the same length.

The other ends of arms 9 are freely pivotally mounted on longitudinally spaced upright trunnion pins 10 on a fixed frame member 11. The arms 9 are constantly retained parallel to each other by a link 12, which is pivotally connected to the arms by pivot pins 13, and which lies parallel to the line between the centers of pins 10 and to the major axis x-x of tool 1. Link 12 and the ends of link 9 in effect, connect slides 7 together and maintains them equidistant at all times. With the described construction, when the central point of the tool, coinciding with the axis of crank pin '2, describes a circle, all the other points of the tool are constrained to describe identical circles.

It is to be understood that other means may be employed to maintain arms 9 parallel at all times. Thus, for example, the link 12 may be replaced by a rigid link longitudinally bowed to clear crank 3, having an effective length between the pin-receiving bores at its ends equal to the distance between pins 10, 10, and pivotally connected to the trunnion pins 8, 8 of the slides 7. With such alternative construction the slides 7 are connected by the link to function, in effect, as a single slide member.

The described tool-driving and tool-guiding means are of advantage, in that the driving means is attached to the tool at only one point, and the tool may thus expand freely, as by thermal expansion under the influence of heat developed during grinding or polishing, without imposing any additional stresses on the driving and guiding mechamsm.

The location of the point of attachment of crank pin 2 to the tool is capable of considerable variation. When pin 2 is mounted near one end of the tool, the apparatus is simpler and more easily made insofar as the motor arrangement is concerned, and a more rapid changing of the tool 1 after it has become worn through use. When the driving pin 2 is located in the neighborhood of the center of the tool, or the other hand, the lateral reactions upon the guides 6 and slides 7, arising from the grinding or polishing forces exerted upon the tool by the workpiece, are at a minimum.

In an alternative embodiment, not shown, the point of attachment of the crank pin 2 to tool 1 is made adjustable longitudinally of the tool. A dynamometer is employed to detect and indicate or record the lateral reactions on the guides. With such apparatus the best position can be found experimentally, in order to miniand the like may be made therein without departing from I the spirit and scope of the invention as will now be apparent to those skilled in the art.

What is claimed is:

1. An apparatus for surfacing sheets of glass, comprising a surfacing tool, and means to give the tool a translatory motion along closed directing curves, said last named means comprising driving means connected at one point only of the tool, and means to guide the other points of the tool so a straight line along the tool remains parallel to itself at all times during the operation of the tool, said last named means comprising at least one slide mounted for reciprocation on the tool, and .idle parallel links pivotally connected at one end to a fixed member and at the other end pivotally connected to said slide.

2. An apparatus as claimed in claim 1, wherein the driving means is connected to the tool between the points of pivotal attachment of the links to the slide.

3. An apparatus as claimed in claim 1, wherein there are two aligned slides on the tool, the ends of the links are connected to the respective slides, the driving means is connected to the tool at a location between the slides, and comprising means to connect the slides and to maintain them equidistant at all times.

4. An apparatus as claimed in claim 3, comprising a further link extending between and pivotally connected to the first recited links parallel to the slides.

5. An apparatus as claimed in claim 4, wherein the further link is connected intermediate the lengths of the first recited links.

6. An apparatus as claimed in claim 4, wherein the tool is rectangular, and the driving means is connected to the tool centrally of the longitudinal axis of the tool.

7. An apparatus as claimed in claim 1, wherein the driving means is connected to the tool adjacent one end thereof.

8. An apparatus as claimed in claim 1, wherein the driving means is connected to the tool for adjustment along the tool.

' 9. An apparatus as claimed in claim 8, comprising a dynamometer connected to detect the lateral reactions between the slide and the guide.

References Cited in the file of this patent UNITED STATES PATENTS 

